Roles of the Surface Layer Proteins of Campylobacter fetus subsp. fetus in Ovine Abortion

Abstract

The role of the surface (S)-layer proteins of Campylobacter fetus subsp. fetus has been investigated using an ovine model of abortion. Wild-type strain 23D induced abortion in up to 90% of pregnant ewes challenged subcutaneously. Isolates recovered from both dams and fetuses expressed S-layer proteins with variable molecular masses. The spontaneous S-layer-negative variant, strain 23B, neither colonized nor caused abortions in pregnant ewes. A series of isogenic sapA and recA mutants, derived from 23D, also were investigated in this model. A mutant (501 [sapA recA ؉ ]) caused abortion in one of five challenged animals and was recovered from the placenta of a second animal. Another mutant (502 [sapA recA]) with no S-layer protein expression caused no colonization or abortions in challenged animals but caused abortion when administered intraplacentally. Mutants 600(2) and 600(4), both recA, had fixed expression of 97-and 127-kDa S-layer proteins, respectively. Two of the six animals challenged with mutant 600(4) were colonized, but there were no abortions. As expected, all five strains recovered expressed a 127-kDa S-layer protein. In contrast, mutant 600(2) was recovered from the placentas of all five challenged animals and caused abortion in two. Unexpectedly, one of the 16 isolates expressed a 127-kDa rather than a 97-kDa S-layer protein. Thus, these studies indicate that S-layer proteins appear essential for colonization and/or translocation to the placenta but are not required to mediate fetal injury and that S-layer variation may occur in a recA strain.

Western Blot Analysis of the IgG-Antibody Response to Acid- Glycine-Extracted Antigens from Campylobacter fetus subsp. fetus and C. jejuni in Naturally Infected Sheep

“…These antigens of C. fetus, including the high molecular weight proteins of 98 to 100, 127 and 149 kDa are present in glycine extracts from C. fetus strains and the diversity of size and structure of the SLP of C. fetus have been well reported (Pei et al 1988;Fujimoto et al 1991;Brooks et al 2002). Grogono-Thomas et al (2000) reported also that most C. fetus subsp. fetus isolates from natural ovine infections express the 97 kDa protein but the 127 kDa and 149 kDa surface layer proteins are rarely seen.…”

“…Sera from rabbits immunized with C. jejuni reacted with a number of components in outer-membrane protein preparations and differed from human sera (Nachamkin and Hart 1985). Recently, an investigation has been reported on the role of S layer protein (SLP) during C. fetus infection in sheep (Grogono-Thomas et al 2000). Different isotypes of antibodies directed against SLPs during ovine infection were also demonstrated with enzyme-immunoassay (Grogono- Thomas et al 2003).…”

“…These proteins of C. fetus represent a family of high molecular weight proteins including proteins of 98 to 100, 127 and 149 kDa that have been demonstrated by SDS-PAGE and Western blot analysis with rabbit immune sera (Pei et al 1988;Grogono-Thomas et al 2000, 2003. Immunoblot studies of C. fetus and C. jejuni with rabbit and human immune sera showed also that C. fetus subsp.…”

The use of enzyme-linked immunosorbent assay and immunoblotting for the detection of Campylobacter fetus immunoglobulins in the cervico-vaginal mucus of female cattle

“…In sheep, Grogono-Thomas et al(2000) suggested that the 97 kDa protein of the S layer is essential for the colonization and passage of C. fetus subsp. fetus through the placenta, but that it is not directly responsible for fetal injury.…”

Campylobacter fetusUses Multiple Loci for DNA Inversion within the 5′ Conserved Regions ofsapHomologs

“…Such recombination may be site specific (21,29,35,54) or may involve repetitive (homologous) DNA sequences (55, 56). Most high-frequency DNA inversions involve site-specific recombination (1,21,29,35,36,71).Campylobacter fetus is a spiral gram-negative microaerophilic bacterial pathogen that interferes with reproductive function in ungulates and can cause extraintestinal infections in humans (28,32,46,59). C. fetus cells are covered by a paracrystalline surface array composed of specialized surface layer proteins (SLPs), ranging in size from approximately 97 to 149 kDa (14, 47).…”